42621409 has 2 divisors, whose sum is σ = 42621410. Its totient is φ = 42621408.

The previous prime is 42621407. The next prime is 42621419. The reversal of 42621409 is 90412624.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 35141184 + 7480225 = 5928^2 + 2735^2 .

It is a cyclic number.

It is not a de Polignac number, because 42621409 - 2¹ = 42621407 is a prime.

Together with 42621407, it forms a pair of twin primes.

It is not a weakly prime, because it can be changed into another prime (42621407) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 21310704 + 21310705.

It is an arithmetic number, because the mean of its divisors is an integer number (21310705).

Almost surely, 2^42621409 is an apocalyptic number.

It is an amenable number.

42621409 is a deficient number, since it is larger than the sum of its proper divisors (1).

42621409 is an equidigital number, since it uses as much as digits as its factorization.

42621409 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 3456, while the sum is 28.

The square root of 42621409 is about 6528.5074098143. The cubic root of 42621409 is about 349.3085915171.

It can be divided in two parts, 4262 and 1409, that added together give a triangular number (5671 = T₁₀₆).

The spelling of 42621409 in words is "forty-two million, six hundred twenty-one thousand, four hundred nine".